Vomit Comet

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The March 30 issue of USA Today featured a story on students of Jim Jordon and George Irwin (Lamar University) flying on the KC-135, known as the “Vomit Comet.” This plane flies in a pattern of 40 flight parabolas to produce periods of “weightlessness.” It is used to train astronauts and was used for filming Apollo 13 capsule scenes. The students took along our 3-Axis Accelerometer, a ULI, and a laptop computer to take the data shown here.

The accelerometers that were oriented roughly horizontally show mostly vibrations. The accelerometer that was oriented more or less vertically is the most interesting. For the first 100 seconds, the plane is traveling horizontally at a steady speed. The accelerometer reads approximately 9.8 m/s (1 g). The plane then applies power and climbs, causing an acceleration reading of up to 1.8 g for a few seconds. The engines are then cut and the plane goes into a near free fall for about 25 seconds. The acceleration reading goes to near zero. Notice that the vibration is reduced on all three accelerometers during this period, because the engines are not working as hard. This pattern is repeated several times on this graph. The Lamar students’ experiment was designed to simulate the tethered launch of a satellite in zero gravity and to measure the acceleration of the satellite.

Stevie Steiner, a former student of Earl Feltyberger (Nicolet HS, WI) and currently a sophomore at the University of Wisconsin, has been studying the formation of aerogels in microgravity conditions. He has been able to get NASA to fly him and his equipment, including our 3-Axis Accelerometer, aboard the “vomit comet.” Here is a sample graph showing acceleration during several parabolic flight paths. A typical parabola is 23-30 seconds of 0 g followed by 45-90 seconds of 1.8 g. (They say too many people pass out at 2 g.) The last two parabola were done to get lunar gravity (1/6 g) and Martian gravity (1/3 g). You can see these on the graph.